YES (VAR x y) (RULES plus(x,s(y)) -> s(plus(x,y)) plus(x,z()) -> x ) (COMMENT Termination is shown by ELPO with interpretations on natural numbers plus_A(x1,x2) = x1 + 2 z_A = 1 s_A(x1) = 1 plus#_A(x1,x2) = 0 z#_A = 0 s#_A(x1) = 0 and precedence: plus > s > z )